1. Field of the Invention
The present invention relates to a method of setting and changing a Receive Channel Set (RCS) of a cable modem (CM), and more particularly, to a method of effectively setting and changing an RCS of a CM.
This work was supported by the IT R&D program of MIC/IITA [2006-S-019-02, The Development of Digital Cable Transmission and Receive System for 1 Gbps Downstream].
2. Description of Related Art
FIG. 1 illustrates a connection structure of a Cable Modem Termination System (CMTS) 101 and cable modems (CMs) 102 to transmit data using a plurality of transmitting/receiving channels according to a conventional art.
Referring to FIG. 1, the CMTS 101 and the CMs 102 to transmit/receive the data are connected with a cable network.
The CMTS 101 is an apparatus for connecting an Internet Protocol (IP) network with the cable network, converts the data received using the IP network into a cable signal, provides the cable signal for the CMs 102, converts the data received from the CMs 102 using the cable network into an IP packet, and transmits the IP packet to the IP network. The CMTS 101 may transmit/receive the data using a plurality of channels simultaneous with the specific CMs 102. Here, available downstream channels need to be reported to the CMTS 101, and the CMTS 101 needs to determine appropriate load distribution and channel bonding service support.
The CMs 102 are apparatuses for providing the Internet and high-speed data communication using the cable network.
The CMs 102 need to recognize which channel set is used for a service from the CMTS 101 in order to transmit/receive the data from/to the CMTS 101.
Hereinafter, a process of setting a Receive Channel Set (RCS) is described. The CMTS 101 receives, from the CMs 102, a registration request message (REG-REQ-MP) including a plurality of Receive Channel Profiles (RCPs). Each RCP logically expresses channel information about a downstream physical layer of the CMs 102, and is shown as a form of a Receive Channel (RC) and a Receive Module (RM).
The CMTS 101 transmits, to the CMs 102, a registration response message (REG-RSP-MP) of encoding a single Receive Channel Configuration (RCC) with reference to an RCP.
The CMTS 101 transmits the registration response message (REG-RSP-MP) to the CMs 102, thereby reporting initialization channel setting of the CMs 102.
In an initial setting, the CMs 102 transmit, to the CMTS 101, the registration request message (REG-REQ-MP) including the plurality of RCPs for first RC acquisition.
The CMs 102 subsequently receive the RCC from the CMTS 101, set downstream receiving apparatuses of the CMs 102 to a corresponding frequency using an RCP-Identification (ID) allocated by the CMTS 101, that is, the specific RCP, acquire a synchronization (SYNC) message, and sequentially acquire downstream channels via a Forward Error Correction (FEC) frame synchronization and Motion Picture Experts Group (MPEG) synchronization process. The CMs 102 subsequently transmit, to the CMTS 101, a registration acknowledgment message (REG-ACK) including a setting result of the RCS.
After registration is completed by the initial setting of the CMs 102, the CMTS 101 may change the RCC of the CMs 102 at any time, thereby adding a channel to the RCS of the CMs 102, or deleting the channel from the RCS, or changing the channel in the RCS.
Specifically, the CMTS 101 transmits, to the CMs 102, a dynamic bonding change request message (DBC-REQ) of a new single RCC.
The CMTS 101 subsequently receives, from the CMs 102, a dynamic bonding change response message (DBC-RSP) including a change result of the RCS, and completes changing the RCS.
The CMs 102 receive the dynamic bonding change request message (DBC-REQ) of the new RCC from the CMTS 101.
The CMs 102 subsequently change the downstream channels again using the received message, and transmit, to the CMTS 101, a dynamic bonding change response message (DBC-RSP) including the change result.
An error may occur during the above-described process of setting and changing the RCS. For example, a CMTS may allocate an RCC not being supported by a CM, or because a channel receive state is unfavorable, the RCC may not be temporarily received even when the RCC is reported as being supported by the CM. Since a plurality of downstream channels is sequentially acquired, a significant delay may occur when a channel setting error occurs once. Also, since the CMTS and the CM transmit/receive the single RCC, the setting and changing of the RCS is difficult when the error with respect to the channel occurs.
Accordingly, a method of effectively setting and changing of the RCS even in an error situation is required.